Trimming mechanism for grinding wheels



Oct. 31, 1939. s. G. BRADY I 2.178.135

TRIMMING MECHANISM FOR GRINDING WHEELS Filed Aug. 29, 1938 2 Sheets-Sheet l INVENTOR SAMUEL e. erupv wim mam ATTORNEYS Oct. 31, 1939. s. G. BRADY 2,178,135

TRIMMING MECHANISM FOR GRINDING WHEELS Filed Aug. 29, 1938 2 Sheets-Sheet 2 INVENTOR SAMUEL G. BRADY WWW ATTOR'NEYS Patented Oct. 31, 1939 I PATIENT oFFicE TRIMMING MECHANISM FOR GRINDING WHEELS Samuel G. Brady, Detroit, Mich, assignor to Gear Grinding Machine Company, Detroit, lllich, a corporation of Michigan Application August 29,

7 Claims.

The invention relates to trimming mechanisms for grinding wheels, such as used in connection with form grinding. It is usual with grinding machines of this character to mount the trimming mechanism in fixed relation to the mounting for the work to be ground, while the grinder wheel is mounted to be movablein its plane of rotation relative to both work and trimmer. Thus, whenever it is necessary to reform the grinding wheel, it is moved into operative relation to the trimming mechanism and after trimming is returned into operative relation to the work. With certain constructions the work and the trimming mechanism are mounted on the main frame of the machine and the grinder wheel on a movable carriage. In other constructions the grinder wheel is mounted on a stationary frame and the work and the trimming mechanism are mounted on the carriage. In either case the grinder wheel is relatively movable through a predetermined path from its position for engagement with the work to its position for trimming. The diamonds or trimming points are usually moved in a plane that is transverse to the plane of rotation of the grinder wheel, and for many forms the mechanism controlling the movement of each trimming point clears grinder wheel in all of its movements. However, for certain forms which it is desired to ime part to the grinder wheel, the center of movement of the trimming point will lie within the body of the grinder wheel when the latter is in trimming position. Obviously, the pivot controlling the movement of the trimmer point cannot be located so as to interfere with the wheel when in trimming position, but it may be laterally offset to clear the wheel, while its axis will still intersect the body of the wheel. However, with such an arrangement this pivotal mounting may still be in the path of the wheel'when it is moved from its trimming position to its working position, or to some other trimming position.

It is the object of the present invention to obtain a construction of trimmer capable of trimming a form such as just described, but which will not interfere with the movement of the grinder wheel. To this end the invention consists in'the novel construction as hereinafter set forth.

In the drawings:

Figure lis a side elevation of my improved trimming mechanism;

Figure 2 is a section partly in elevation and substantially on line 2-2 of Figure 1;

Figure 3 is an end elevation of the means for 1938, Serial No. 227,394

accurately holding the trimming mechanism in position for operation;

Figure 4 is an elevation similar to Figure 1 showing the mechanism withdrawn to avoid interference with cooperating trimming mechanisms;

Figure 5 is a plan view of a portion of Figure 1.

As specifically illustrated, my improved mechanism is designed for trimming an arcuate surface lying in an axial plane of the grinder wheel and where the center of the arc is within the body of the wheel. This specific construction is not, however, essential to my invention which is broadly applicable to any construction where it is desirable to remove the trimmer from and subsequently to accurately restore it to its operative position.

As illustrated, A is a portion of the frame of a grinding machine and B and B indicate in dotted lines grinder wheels of different diameters in position in relation to this frame during the trimming operation by one of the diamond points. C indicates a vertical plane in which the axis of the wheel B must be arranged while portions of its surface are trimmed by other mechanism, not shown. D and D indicate the path of movement of the axis of the wheel in traveling from the position indicated in dotted lines to its position in the plane C, and also in its movement toward the working position, not shown. E is the trimming point and F is the axis around which this point must rotate in traveling through its trimming path. As this axis F intersects the body of the wheel, it is obvious that the supporting means cannot include a journal located in the plane of movement of the point E. However, a pivot may be laterallyoifset from the plane of movement of the point to control the same without interference with the wheel. This introduces a further problem inasmuch as the pivot or journal would obstruct the path of the wheel during its movement from the position indicated at B to its position with its axis in the plane C. I have, therefore, devised a construction in which the operating mechanism for the point E is mounted on a movable frame capable of being withdrawn from the path of the grinder wheel during its movement from one trimming position to another.

Generally described, my improved mechanism includes a shaft G which is journaled in suitable bearings in the frame A, an arm H extending upward from the shaft G to support the point E with the means for controlling the movement thereof, and a bell crank arm I also secured to the shaft and determining the position of the arm H. The shaft G is journaled in a bearing J which is of sufficient length to hold the arms H and I in a fixed plane, while permitting movement in this plane upon the revolution of the shaft to withdraw the trimmer from the path of movement of the grinding wheel. It is, however, of the utmost importance that the movement of the arm H should be exactly limited so that the trimmer is always in the same position when operating. This is accomplished by the following construction.

Secured to the end of the frame A is a bracket member K which projects outward therefrom and has at its outer end an angle portion K. K is a threaded member engaging a correspondingly threaded vertically extending aperture in the portion K and constituting an adjustable stop. K is a pin projecting laterally from the outer end of the bell crank arm I in a position to contact with the stop K K is an arm pivotally attached to the portion K and having a V- shaped notch K for engaging the pin K on its side opposite the stop K K is a clamping screw pivotally attached at K to the member K, which screw passes through a bifurcated portion of the member K and is provided with a wing nut K through which the pin K may be tightly clamped against the stop K On the other hand, by releasing the nut K and disengaging the clamping screw K from the member K the pin K is released, permitting the swinging of the bell crank arm I and the lowering of the arm H.

The diamond point E is carried by a member L which is pivotally mounted upon the upper end of the arm H to permit movement of the point about the axis F. As this pivot determines the path of movement of the point, it is necessary to construct the same with extreme accuracy. This is accomplished by providing the member L with an integral trunnion L which passes through an aperture in the member H. Surrounding the trunnion within the aperture are bushing members L L which are formed with extreme accuracy and very limited clearance to hold the trunnion to an exact axis of rotation. A shoulder L on the member L bears against these bushings and the member H, while a head member L secured to the trunnion L by a screw L bears against the opposite ends of the bushings and the member H. The bushing L is held from rotation by a screw L engaging an aperture in the member H, and a dust shield L clamped by this same screw engages a grooved collar L on the member L to protect the trunnion from the dust of the grinder. The member L has an outwardly extending arm L which is apertured to receive the shank E of the diamond point E. This shank is adjusted by a screw E and is held in its adjusted position by a set screw E The member L is also provided with a shoe L which engages a segmental groove guide H on the member H to further increase the accuracy'of movement of the point. A handle L secured to and extending downward from the member L provides a convenient means for moving the same.

The length of radius of the diamond point with respect to the axis around which it turns may be varied by the adjusting screw E I have also provided means for adjusting the position of the axis F of the trunnion L with respect to the frame A and shaft G. This is accomplished by forming a hub I which is integral with the arm I and is provided with an upwardly extending portion I I is a tongue on the portion I which engages a corresponding groove in the arm H to permit of longitudinal adjustment; A headed screw I passing through a slot H in the mem ber H and engaging a threaded aperture in the member I serves to clamp these members together. There is also an adjusting screw I pass ing through a threaded aperture in the hub I and bearing against the lower end of the member H by which this member may be accurately adjusted.

With the construction as described, whenever it is necessary to trim the grinder wheel by the diamond point E, the arm H is first lowered to clear the path of the grinder wheel, while it is moved into a position for trimming. This is accomplished by releasing the clamping member K and permitting the arm I to be swung downward, thereby rocking the arm H from vertical to horizontal position. As soon as the grinder wheel is in position, the arm I is again swung upward and the pin K is clamped against the stop K which accurately positions it and also the member H. The desired length of radius for the trimmed arc is obtained by adjusting the screw E and the position of the point E with respect to the axis of the grinder wheel is adjusted by the screw I It may also be desirable to accurately limit the length of the are through which the trimming point travels which is accomplished by adjustable screw stops M engaging a lug M projecting rearward from the member L. This lug engages a segmental recess H in the member H, and the screw stops M engage threaded apertures in said member to project into opposite ends of said recess.

What I claim as my invention is:

1. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of trimming mechanism located on said frame in the latter position comprising a bell crank lever having an upwardly extending arm and a laterally extending arm, a shaft on which said lever is mounted, bearings on said frame in which said shaft is journaled, a trimming head pivotally mounted on the upper end of said upwardly extending arm to be located in the path of said grinder wheel when moved from one position to another, an arm projecting laterally from said trimming head into the vertical axial plane of said grinding wheel when in trimming position, a trimming point mounted on said arm in the said vertical axial plane, an adjustable stop on said frame for limiting the movement of said laterally extending arm of said bell crank lever, and means for normally clamping said arm in contact with said stop, said means being disengageable to permit the swinging of said bell crank lever about the axis of said shaft to bodily move said trimming head out of the path of said grinder wheel.

2. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of trimming mechanism located on said frame comprising a bell crank lever having an upwardly extending arm and a laterally extending arm, a shaft on which said bell crank lever is mounted, a journal bearing in said frame for said shaft, a trimming head mounted on said upwardly extending arm and normally located in the path of said grinder wheel when moved from one position to another, an arm projecting laterally from said trimming head in a position to clear said grinder wheel and extendling into the vertical axial plane thereof when in trimming position, a trimming point mounted on said arm, a pin mounted on the free end of said laterally extending arm, a bracket projecting from said frame, a stop adjustably secured to said bracket located to contact with said pin, a clamp swingably secured to said bracket for engaging said pin to hold the same in contact with said stop, said clamp when disengaged permitting the downward swinging of said laterally extending arm to carry said upwardly extending arm and the trimming mechanism mounted thereon out of the path of said grinder wheel.

3. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of a trimming mechanism located on said frame in the latter position and comprising a lever pivotally mounted on said frame and provided with an upwardly extending arm, a trimming head pivotally mounted on said upwardly extending arm in a position to be in the path of said grinder wheel when moved from one position to another, the axis of the pivotal connection intersecting said grinder wheel when in trimming position, an arm projecting laterally from said trimming head into the vertical axial plane of said grinder wheel when in trimming position and located to clear said wheel, a trimming point carried by said arm and adjustable to vary its radial length from the pivot axis, means for vertically adjusting said trimming head on said vertically extending arm to adjust said trimming point with respect to the periphery of said grinder wheel, a stop on said frame for limiting the movement of said lever, said stop being adjustable to accurately determine the position of said lever when in contact therewith, and means for detachably clamping said lever in engagement with said stop whereby upon the release of said clamping means said lever may be moved to carry said trimming mechanism out of the path of said grinder wheel.

4. The combination with a frame and grinder wheel movable in relation to said frame from one position to another, of trimming mechanism located on said frame comprising a bell crank lever pivotally mounted on the frame and havin an upwardly extending arm and a laterally extending arm, a trimming head pivotally mounted at the upper end of said upwardly extending arm, adjustment means for the pivotal mounting of said head with respect to the pivotal mounting of said lever, an arm projecting laterally from said trimming head into the vertical axial plane of said grinder wheel when in trimming position, a trimming point mounted on said arm, means for adjusting said point to vary its radial distance from the axis of the pivot of said head, a stop on said frame for limiting the movement of said laterally extending arm of said bell crank lever, and means for detachably clamping said arm in contact with said stop.

5. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of trimming mechanism located on said frame comprising a bell crank lever pivoted on the frame and having an upwardly extending arm and a laterally extending arm, an adjustable extension on said upwardly extending arm, a trimming head pivotally mounted on said extension, an arm projecting laterally from said trimming head into the vertical axial plane of the grinder wheel when in trimming position,

a trimming point mounted on said arm, means for adjusting said point to vary the radial distance of the same from the axis of the pivot for said head, adjustable means for limiting the movement of said head about its pivot to vary the length of the trimming are, an adjustable stop on said frame for limiting the movement of the laterally extending arm of said bell crank lever, and means for detachably clamping said arm in contact with said stop.

6. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of a trimming mechanism located on said frame and comprising a bell crank lever pivoted on said frame and having an upwardy extending arm and a laterally extending arm, an extension on said upwardly extending arm, a pivot carried by said extension with its axis parallel to the axis of the pivot of said bell crank lever, means for adjusting said extension to vary the distance between the axes of said pivots, a trimming head mounted on the pivot on said extension, an arm projecting laterally from said head into the vertical plane of the grinder wheel when in trimming position, a trimming point on said arm, means for adjusting said trimming point to vary the radial distance between the same and the axis of the pivot for said head, a handle member for moving said head about its pivot, a guide for maintaining said head in a fixed plane during said movement, means for variably limiting the movement of said head to determine the length of the trimming arc, a stop on said frame for limiting the movement of said laterally extending arm of said bell crank lever, and means for detachably clamping said arm in contact with said stop.

7. The combination with a frame and a grinder wheel movable in relation to said frame from one position to another, of trimming mechanism located on said frame and comprising a bell crank lever pivoted on the frame and having an upwardly extending arm and a laterally extending arm, trimming mechanism mounted at the upper end of said upwardly extending arm, a member extending from said frame adjacent to the free end of said laterally extending arm of said bell crank lever, a stop adjustably secured to said member, a pin on said laterally extending arm for engaging said stop to limit the movement of said arm, and a clamp pivotally connected to said member for detachably holding said pin in engagement with said stop.

SAMUEL G. BRADY. 

